Slide 1
A chemical synapse passes a message between cells
A synapse is a communication junction. At a chemical synapse, a neuron, or nerve cell, releases a messenger that influences a neighbouring cell.
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An axon carries signals away from a neuron’s cell body toward its terminals. Dendrites commonly receive inputs, although real neural connections are more varied than this introductory pattern.
Slide 2
An electrical arrival triggers chemical release
When a signal reaches the nerve terminal, calcium can enter through channels. This helps small sacs called vesicles release neurotransmitter, a chemical messenger, into the gap.
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The gap is called the synaptic cleft. Messenger molecules cross it by diffusion and bind receptors on the receiving membrane; the two cells do not need to fuse together.
Slide 3
The receptor determines the receiving cell’s response
A neurotransmitter’s effect depends on the receptor it meets. A receiving cell may become more or less likely to send its own signal.
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A neuron combines inputs arriving at different locations and times. A small response from one connection need not be enough to initiate the larger electrical event called an action potential.
Slide 4
Clearing the messenger separates one event from the next
Messenger molecules are removed, taken back up or broken down. Clearing them helps a synapse distinguish one event from the next.
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Some synapses use direct electrical connections instead of a released chemical messenger. This alternative permits rapid transfer of current and can help synchronize groups of cells.
Slide 5
Changing connection strength changes the network
Synapses are adjustable communication points. Changes in their strength alter how a network responds to later patterns of activity.
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The nervous system also contains supporting cells called glia. Neurons depend on this surrounding tissue, so a network is more than a collection of isolated wires and switches.
Sources
- Communication Between Neurons
OpenStax, Rice University
- Nervous Tissue
OpenStax, Rice University